The present invention relates to video monitoring and reapposition monitoring apparatus and methods. More particularly, the present invention relates to monitoring apparatus and methods of video or other imaging technology for use in applications in which changes in relative spatial relationship of features of a biological tissue are to be observed, such as in surgical reapposition or closure of an incision and other medical or scientific procedures.
Without limiting the scope of the invention and its numerous intended applications, the background of the invention is described specifically in the context of eye surgery. During cataract surgery for example, it is desirable to close the incision so that when the eye heals the patient is left with a curvature of the cornea that either corrects pre-surgical astigmatism or avoids introducing astigmatism. Astigmatism occurs when one meridian of the cornea has a steeper radius of curvature than the median perpendicular to it.
Presently, the corneal curvature before surgery is measured and the meridian identified using an optical device called a keratometer, see for example U.S. Pat. Nos. 4,429,960 and 4,157,859. It has been known as a general matter that adjusting the suture tension and the healing process itself cause changes in astigmatism. A few days following surgery the eye is examined again using the keratometer. Depending on the results of the followup exam, the suture tension is adjusted so that when the eye has healed the astigmatism will be at least partially corrected. Because the value of corneal curvature determined by the keratometer depends on intracorneal pressure which the surgeon can only roughly restore by injection of fluid into the anterior chamber of the eye, and accuracy also depends on an absence of external pressures on the eye, the postoperative astigmatism value so determined is relatively uncertain at the conclusion of the operation and for a period of time thereafter. As a result, the patient's astigmatism may be only partially corrected, if at all.
It is believed that improvements are desirable in apparatus and methods for monitoring changes in relative spatial relationship of features of biological tissue such as in surgical reapposition and other medical or scientific procedures.
Two examples of prior art video monitors generally intended for use in the surgical operating room are disclosed in patent Nos. 4,598,311 and 4,594,608.